stdlib atom

1 files changed, 64 insertions, 0 deletions

diff --git a/src/atom.gleam b/src/atom.gleam
new file mode 100644
index 0000000..e887a01
--- /dev/null
+++ b/src/atom.gleam
@@ -0,0 +1,64 @@
+import expect
+
+pub external type Atom;
+
+pub enum AtomNotLoaded =
+  | AtomNotLoaded
+
+pub external fn from_string(String) -> Result(Atom, AtomNotLoaded) =
+  "gleam__stdlib" "atom_from_string";
+
+test from_string {
+  "ok"
+  |> from_string
+  |> expect:is_ok
+
+  "expect"
+  |> from_string
+  |> expect:is_ok
+
+  "this is not an atom we have seen before"
+  |> from_string
+  |> expect:equal(_, Error(AtomNotLoaded))
+}
+
+// This function can create a new atom if one does not already exist for
+// the given string. Atoms are not garbage collected so this can result
+// in a memory leak if called over time on new values
+//
+pub external fn create_from_string(String) -> Atom =
+  "gleam__stdlib" "atom_create_from_string";
+
+test create_from_string {
+  let ok = fn(x) { Ok(x) }
+
+  "ok"
+  |> create_from_string
+  |> ok
+  |> expect:equal(_, from_string("ok"))
+
+  "expect"
+  |> create_from_string
+  |> ok
+  |> expect:equal(_, from_string("expect"))
+
+  "this is another atom we have not seen before"
+  |> create_from_string
+  |> ok
+  |> expect:equal(_, from_string("this is another atom we have not seen before"))
+}
+
+pub external fn to_string(Atom) -> String =
+  "gleam__stdlib" "atom_to_string";
+
+test to_string {
+  "ok"
+  |> create_from_string
+  |> to_string
+  |> expect:equal(_, "ok")
+
+  "expect"
+  |> create_from_string
+  |> to_string
+  |> expect:equal(_, "expect")
+}